The present invention relates to agricultural implements and more particularly relates to a combined hitch adapter and transmission assembly for allowing a towing tractor, having a power take-off or PTO shaft coupled to an input shaft of the transmission to turn sharply without damaging driven components of the implement nor the drive for such components.
In co-pending U.S. patent application Ser. No. 927,467 filed on 6 Nov. 1986 there is disclosed an agricultural implement including a hitch adapter having a drawbar coupled to the implement draft tongue by a hitch ball connector. An implement drive transmission includes a gearbox or housing mounted to the draft tongue for pivoting about an upright axis passing through the bal connector. An input shaft is mounted in the housing for rotation about an axis extending perpendicular to the upright axis and is adapted for connection to a tractor PTO shaft. A steering arm is vertically pivotally attached to the transmission housing and carries a ball slidably located in a fore-and-aft extending guide channel fixed to the adapter and having sidewalls shaped complementary to the ball. While the steering arm and guide channel cooperate so as to maintain the input shaft in a disposition which would be parallel to the tractor PTO shaft during turning of the hitch adapter about the upright axis, it has been found that the steering arm and guide channel will effect an incorrect "steering" of the input shaft when the hitch adapter rolls about an axis extending crosswise to the upright axis.